Ok,

I've been bashing my head against the wall trying to figure out what's causing my engine to knock and ping for the past month. I'm hoping that someone in the community might be able to help me. I only notice it mainly between 3000-4000 RPM. I can lug the motor and no knock, just under WOT between 3-4000rpm

What I've tried so far:

#1- Switching filling stations, I've run three tanks of gas through from different stations all 91 octane. Cheveron, Phillips 66, Shell

#2- Ran additives: Techron additive first tank. Second tank octane booster. Third tank nothing. Fourth tank added Seafoam fuel additive (just did this today)

#3- Went back to stock spark plugs from the NGK Irridium and reset ECU (did that last night)

#4- Had my Mini Dealer check my air/fuel mixtures and ran a engine diagnostic and everything checked out fine

So far none of these things have made much of a difference...

Does anyone out there have a similar set up as me that has experience knock and ping? If so what was the remedy?

My mods are in my sig, I do have the aerogel heat blanket underneath my DFIC. Thats the only thing not listed

Any help at all would be greatly appreciated

 

Man, do I feel your pain. When I added a 2% crank pulley to the 15% SC reduction pulley, I started pinging, and went through many of the same steps as you to try to resolve it, but also went with a custom dyno-tuned Unichip and installing a methanol-water injection system.

Which serpentine belt are you using, and when was the last time it was replaced? At 25K miles, I replaced the OEM belt (1388mm) with a shorter Gatorback 4060537 belt (1365mm), and that has reduced the amount of pinging I have by approximately 75-80%. The OEM belt wasn't worn out at 25K, but looked like it had stretched out a bit. Your 17% pulley setup may require a shorter belt than what you are running now, or may be due for a new belt.

Another item to check is the belt tensioner. When it rattles, it may sound similar to pinging, and it does have a tendency to rattle at 3-4K RPM. 002 has stated that in this post:
https://www.northamericanmotoring.co...17&postcount=6

 

Thanks for the response Latte, and holy crap.... this is sure a pain in the butt.

I am running a napa belt #060539 and It was installed about 10000-12000 miles ago when I added the pulley. I appreciate the pointer to look at the tensioner. Maybe I have some stretch causing some slippage eh?

Can the Gatorback belts be purchased at a local auto parts store? Maybe a move to a Napa #060535 smaller belt would be better?

I guess I need to see if its fitting loosely before making any decisions. I sure appreciate the pointer tho

 

I live in Southern California and in the summer months I had pinging with my 17% pulley, so I believe it is related to additional heat being generated. To [FONT='Calibri','sans-serif']alleviate the issue, I added a larger air divertor and a water sprayer. This seems to have eliminated the pinging.[/FONT]

 

I live in Utah and its 20 degrees here

 

Will belt slippage really cause the engine to knock and ping? Seems to me that the engine would run more rich if the sc wasn't spooling as fast

I went out and looked at my belt. I guess I'm unsure where to look to determine if one or more "holes" are showing? Anyone out there have a pick of what I should be looking at? Do I have to remove the well cover to see it?
From feeling the play in the belt it feels pretty damn tight and I can't see any signs of wear or damage.

As for the link you posted about the Idler pulley and tensioner making the noise. I had a weird rattle about 2 months ago and took it in. It was in fact the idler pulley, it had a burr on it or something causing it to make noise. This noise is way different. I'm pretty sure its a knock/ping.... hard to determine without a dyno or a way to test it under load. It doesn't make the noise just by revving the engine stationary

Thanks for the help

 

I had my doubts, too, regarding belt slippage causing pinging... I've got some theories for how slippage might cause some pinging, but admittedly, I am not sufficiently familiar with the workings of the drivetrain, engine timing, and anti-knock sensors.

The number of holes showing in the tensioner assembly does not always reflect whether the belt is stretched (you . I had 3/4 of a hole showing the entire time I was running the OEM belt. The Gatorback initially showed a full hole, then also went to 3/4 of a hole after a few hundred miles, but with reduced pinging and much better power delivery.

This is the photograph that's been passed around all over NAM for the holes in the tensioner (I think the photo credits go to CmdrVimes). You should be able to see in there with nothing more than a flashlight, if necessary - the photograph shows about half a hole right above the spring:

 

What about your tranny?...I know some knock and pings that many think is the motor is the flywheel/clutch/throwout bearing.... BTW, How's the car holding up after everything???

 

Dude, the car is 100% after the accident. I never thought it would be, and like you thought I would experience some sort of issues. I'm glad to say that the car has suffered no ill affects. We have an amazing body shop that I will direct everyone I know too because of the amazing job they did on my car. Daves body shop here in West Jordan Ut! Freaking amazing work ethic, and overall workmanship.

The car has a ton of power and pulls strong.... just this damn knocking that appeared...

Interesting stuff about the throwout... Never would have thought about it. It is was making a squeaky type noise when the clutch was depressed last summer. Especially when it was hot here. I just got back from my dealership and after driving it around with a mechanic he thinks its a engine knock as well.

He's wondering if I might need to upgrade to the JCW injectors, he thinks there's a possibility of running lean with my 17%. Any idea on this ??


Sonofa freak this is an annoying problem

 

Thanks for that image Latte, I had the dealership check the tension on the belt while I was there today and they said it was fine

Who the hell knows at this point... I am interested in the thought I might be running lean and need bigger injectors. Guess the only way to know that is to put it on a dyno and hook it up to see what its doing eh?

 

It has nothing to do with the belt. Pm me for some details.

 

PM sent

 

Did your Pinging start when the OUTSIDE Ambient tempetures went below 40deg F??

 

Shoot...some 380's or 440's would be a plus and a way to get some mods by the wife...CAUSE THEY HAVE TO BE DONE...

 

I would bet that the dealer did little more than check the hole in the belt tensioner.

Putting the car on the dyno would allow you to visualize any belt slippage and timing retard on the graph (spikes and dips instead of a smooth curve). Alternately, changing the belt is a $20 DIY job that takes less than an hour.

I find it hard to believe that you'd be running lean on your current mods, unless your injectors are clogged - but then, you've been using fuel additives that ought to have cleaned out the injectors. I did the JCW injectors too, and AFR remained below 12 up to 4.5K RPMs then dipped below 10 at that point - the pinging still persisted.

Just sharing my experiences with eliminating/reducing pinging, so take all this with a grain of salt. There are so many contributing factors, it can take a while to go through them all. However, I've thrown a lot of money in chasing down the pinging, and after a significantly lighter wallet, a $20 belt managed to resolve almost all the pinging (the remainder lies with heat management, IMHO). Of course, YMMV. I hope that some of the more technical members will step in here.

 

How does that old nursery limerick go?

"Secrets secrets are no fun. Secrets secrets hurt someone."

 

It did seem to happen when the temps dropped yes. I didn't have any trouble this summer and the temps were over 100deg F

 

I do remember a few threads a long time ago (3 years or so) that people had AUTO tranny's goin out in the harsh cold. But, on that, I think they didnt let them warm all the way up to normal op temp.

 

Done that!
You have to use a higher octane gas, period. Whenever I fill up with 91 octane, I add 2 gallons of 109 octane racing fuel to get rid of those knocks and pings that occur around 3k rpm. I even had my ecu custom tuned on a dyno and it still pinged. Tethered to racing gas.

 

PM

 

Lots of secrecy in this thread

 

Well, A couple good ideas have been thrown my way as to the problem and solution.

I live in Utah and its about 30 degrees here now. The suggestion was made that with that cold of temp outside my engine is able to force more air in and the colder the air = more density. In theory I could be putting more air than gas in causing the knock by running lean. Possible solution would be to increase fuel flow with some larger injectors possibly 380 JCW's. I would of course then need a custom tune to take advantage of the injectors and increased fuel.

This all makes sense to me because I started having this problem when the air outside was in the 30's-40's. Not sure if this is fact of fiction and neither is the person that made the suggestion but it makes sense and is a great place to start. Nothing else I have done to this point has made a difference

I am going to get my car on a local dyno to see exactly whats going on. I want to make sure its a F/A problem and not something mechanical.

If anyone else has nay ideas I would sure welcome them and thanks to everyone thats made suggestions

 

Sounds like you need a tune .

Putting in 380's with your level of mods isn't really going to make a difference. Your car is probably pinging because it's not tuned properly. You can't increase boost pressure by 50% and not expect issues with stock software.

I'd spend money on a quality dyno tune before I spent another dime on additives, more expensive gas, or any more parts.

 

YES , A tune will solve your problem. Unless your fuel pump is going out. Then again , a base dyno will show your a/f ratio and you will see if your car is getting enough fuel. If not , dont go ahead and add bigger injectors. Check your fuel pressure which should be at 51psi. It might be around 40 and that will tell you that you need a fuel pump. Therefore, your car starts pinging around 3k cuz you arent getting the right amount of fuel.

 

Try an upper intake cleaning, it eliminated my pinging for a couple of months